Smallest chameleons in the world discovered

Living miniature lizards live on Madagascar

Young Dwarf Chameleon Brookesia micra on a fingertip © Frank Glaw
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In Madagascar, researchers have discovered the world's smallest lizards. The four new types of dwarf chameleons are less than 20 millimeters in size, the smallest type measures only 16 millimeters from the head to the end of the body. She is small enough to stand on a matchstick head. The species Brookesia micra belong thereby to the smallest vertebrates world-wide. The newly discovered dwarf chameleons are amazing cases of extreme miniaturization, the scientists report in the journal "PloS ONE". Only the miniature frogs recently discovered in Madagascar were only a few millimeters smaller.

The group of German and US scientists had discovered the new miniature oxen on expeditions in northern Madagascar. There grows both rainforest and dry deciduous forest on a very kleinteiligen, rugged limestone substrate. Unlike their larger relatives, the dwarf chameleons found there live on the ground in the leaf litter. They are well camouflaged by their inconspicuous brownish color.

"At night they then climb on low branches and parts of plants to sleep there, " report Frank Glaw of the Zoological State Collection Munich and his colleagues. Their miniature dwarf chameleons do not use their short tail as climbing aid, just like their tree-living relatives, but use it as their fifth leg while running.

Extremely small distribution areas

As the researchers report, the range of the four new miniature species is extremely small. Each of these species was found only in a single location on the northern tip of Madagascar. "These close ranges are widespread among animals in Madagascar, but there are few examples that are as extreme as the miniaturized Brookesia species, " write Glaw and his colleagues.

Portrait of the dwarf chameleon Brookesia micra © Frank Glaw

Genetic analyzes also revealed that the genome of the four dwarf chameleon species differs greatly, but is very uniform within each species. "This is best explained by the fact that the local populations of these species hardly moved and were genetically isolated, " say the scientists. They assume that the lineages of these species probably already separated 10 to 20 million years ago. Together with the newly discovered species, one already knows eleven forms of small Brookesia-Cham leons in Madagascar. display

Life on the island could have promoted miniaturization

The smallest species, Brookesia micra, occurs only on the small island Nosy Hara off the coast of northern Madagascar. According to the researchers, so-called island dwarfing could be responsible for their extreme miniaturization. This biological phenomenon often leads to smaller and smaller numbers of small islands without predators in the course of evolution.

Madagascar is already known for some unusually small animals, the researchers say. Thus, there live some species of nocturnal mouse lemurs, which are among the smallest primates of the earth. Even the frogs, which are considered the smallest known vertebrates, have been found on Madagascar. (PloS ONE; 2012; doi: 10.1371 / journal.pone.0031314)

(Public Library of Science, 16.02.2012 - NPO)